Anionic surfactants such as soaps, sodium dodecylbenzenesulfonate, polyoxyethylene alkylphenyl ether sulfuric acid ester salts, and polyoxyethylene alkyl ether sulfuric acid ester salts and nonionic surfactants such as polyoxyethylene nonylphenyl ether and polyoxyethylene alkyl ethers have hitherto been utilized as emulsifiers for emulsion polymerization. However, polymer films obtained from polymer dispersions which are produced by using these emulsifiers have problems in that the films are poor in water resistance and adhesive holding power because the emulsifiers used remain in a free state in the polymer films. As an improvement method for the above problems, many reactive emulsifiers having a copolymerizable unsaturated group have been proposed (for example, patent documents 1 to 3).
Reactive emulsifiers having an acrylic group or methacrylic group as a copolymerizable unsaturated group have been proposed in conventional techniques.
However, these emulsifiers have a problem in that the emulsifiers impair polymerization stability during emulsion polymerization although they are excellent in terms of copolymerizability with monomers. For example, the emulsifiers have problems in that agglomerates are formed in an increased amount during the emulsion polymerization and that the particles yielded are coarse and have poor stability over time. With respect to reactive emulsifiers having an allyl group as a copolymerizable unsaturated group, there are cases where the reactive emulsifiers are poor in copolymerizability with monomers, depending on the kinds of monomers and polymerization conditions, and there are unsolved problems in that polymer films having fully satisfactory water resistance and adhesive holding power are not obtained from the polymer dispersion and that the foaming of the polymer dispersion causes process troubles. These problems frequently arise especially in the case where the monomers being polymerized by emulsion polymerization include styrene, and in the commercial production, there is a strong desire for improving these problems.